Automobile
An automobile is a self-propelled passenger-carrying vehicle
designed to operate on ordinary highways and usually supported
on four wheels. Power is provided in most modern cars by an
internal combustion engine fuelled by gasoline (vaporized
and premixed with a suitable quantity of air). This is ignited
in the (usually 4, 6, or 8) cylinders of the engine by spark
plugs, fired in the appropriate sequence.
The gas supply and thus the engine speed is controlled from
the accelerator pedal. The driving power is communicated to
the road wheels through the transmission which includes a
clutch (in the case of a manual transmission), enabling the
driver to disengage the engine without stopping it, a gearbox
(allowing the most efficient use to be made of the engine
power), various drive-shafts (with universal joints), and
a differential which allows the driving wheels to turn at
marginally different rates in cornering.
Steering is controlled from a hand wheel which moves a transverse
tie rod mounted between the independently-pivoted front wheels.
Service brakes of various types are mounted on all wheels,
an additional parking-brake mechanism being used when stationary.
In modern automobiles service brakes and steering may be power-assisted
and the transmission automatic rather than manually controlled
with a gearshift (see automatic transmission).
Although the first propelled steam vehicles were built by
the French army officer Nicholas-Joseph Cugnot in the 1760s,
it was not until Karl Benz and Gottlieb Daimler began to build
gasoline-powered carriages in the mid-1880s that the day of
the modern automobile dawned. The Duryea brothers built the
first US automobile in 1893 and within a few years several
automobile manufacturers, including Henry Ford, had started
into business. The Ford Motor Company itself was founded in
1903, pioneering the cheap mass-market auto with the Model
T of 1908. The automobile industry expanded fitfully until
the 1960s, improving automobile performance, comfort, and
styling, but more recently has been forced to pay more attention
to safety, environmental factors, and energy conservation.
Aerodynamics, more efficient engines, and better transmission
have been the focus of development.
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